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Publicações

Publicações por PHT

2009

A SIMPLE SMART COMPOSITE USING FIBER BRAGG GRATING SENSORS FOR STRAIN AND TEMPERATURE DISCRIMINATION

Autores
Frazao, O; Oliveira, R; Dias, I;

Publicação
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS

Abstract
A smart laminated composite with a simple geometry was produced with embedded fiber Bragg grating sensors. The smart structure is composed of two Bragg gratings located in regions of different thicknesses of the laminated composite. Although one of the Bragg gratings is embedded between two layers, the other is embedded in jour layers. When the strain is applied to the smart composite, different response is obtained. Because of this characteristic it is possible to discriminate strain and temperature using a traditional matrix method. To reduce the inherent error, an artificial neural network approach is proposed that will improve the strain and temperature measurement discrimination when using this new configuration. These instrumented carbon fiber laminates can be used for monitoring of reinforcement and protection of structures. (C) 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 235-239, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23990

2009

Optical Fibre Sensing Networks

Autores
Santos, JL; Frazao, O; Baptista, JM; Jorge, PAS; Dias, I; Araujo, FM; Ferreira, LA;

Publicação
2009 SBMO/IEEE MTT-S INTERNATIONAL MICROWAVE AND OPTOELECTRONICS CONFERENCE (IMOC 2009)

Abstract
This presentation gives a review of the main concepts behind fibre optic sensing networks. Some important application areas are mentioned, such as the monitoring of oil fields, of large Civil Engineering structures, as well as of natural environments. Then, it will be addressed the potential relevance of this technology in domains of increasingly social importance, such as Health and Elderly Care, particularly in the development of Personal Health Systems.

2009

Optical characterization and composition of abdominal wall muscle from rat

Autores
Oliveira, L; Lage, A; Clemente, MP; Tuchin, V;

Publicação
OPTICS AND LASERS IN ENGINEERING

Abstract
Complete optical characterization of biological tissue is desirable to develop clinical methods using optical technologies. Particularly, to develop optical clearing methods in biological tissues, it is necessary to know the composition of the tissue, the percentage of each constituent and corresponding refractive indexes. To obtain such information for rat muscle, we used a simple method to characterize tissue constituents for both content percentage and refractive index. The study consisted on measuring mass with a precision weighting scale and the refractive index with an Abbe refractometer during tissue dehydration. With the collected data, we used a theoretical model to calculate the refractive index and percentage for both interstitial fluid and solid part of the rat muscle. The results obtained are in good agreement with data published by other authors, and were considered of vital information for the optical clearing studies that we planned to perform.

2009

Study of vital sign monitoring with textile sensors in swimming pool environment

Autores
Silva, M; Catarino, A; Carvalho, H; Rocha, A; Monteiro, J; Montagna, G;

Publicação
IECON: 2009 35TH ANNUAL CONFERENCE OF IEEE INDUSTRIAL ELECTRONICS, VOLS 1-6

Abstract
This paper presents the results of a series of experiments aiming at the optimisation of vital sign monitoring using textile electrodes to be used in a swimsuit The swimsuit will integrate sensors for the measurement of several physiological and biomechanical signals, this paper will focus on ECG and respiratory movement analysis The data obtained is mainly intended to provide tools for evaluation of high-performance swimmers, although applications can be derived for leisure sports and other situations A comparison between electrodes based on different materials and structures, behaviour in dry and wet environments, as well as the behaviour in different extension states, will be presented The influence of movement on the signal quality, both by the muscular electrical signals as well as by the displacement of the electrodes, will be discussed The final objective is the integration of the electrodes in the swimsuit by knitting them directly in the suit's fabric in a seamless knitting machine

2008

Intelligent optical sensors using artificial neural network approach

Autores
Dias, I; Oliveira, R; Frazao, O;

Publicação
INNOVATION IN MANUFACTURING NETWORKS

Abstract
This work present and demonstrated an applications of artificial neural network approach in optical sensing. The conventional matrix method used in simultaneous measurement of strain and temperature with optical Bragg gratings is compared with artificial neural network approach. The alternative method is proposed for reduced the error.

2008

A simple mixture to enhance muscle transmittance

Autores
Oliveira, L; Lage, A; Clemente, MP; Tuchin, VV;

Publicação
OPTICAL TECHNOLOGIES IN BIOPHYSICS AND MEDICINE IX

Abstract
Skeletal muscle is a fibrous tissue composed by muscle fibers and interstitial fluid. Due to this constitution, the muscle presents a non uniform refractive index profile that origins strong light scattering. One way to improve tissue transmittance is to reduce this refractive index mismatch by immersing the muscle in an optical clearing agent. As a consequence of such immersion tissue also suffers dehydration. The study of the optical clearing effect created by a simple mixture composed by ethanol, glycerol and distilled water has proven its effectiveness according to the variations observed in the parameters under study. The effect was characterized in terms of its magnitude, time duration and histological variations. The applied treatment has created a small reduction of the global sample refractive index that is justified by the long time rehydration caused by water in the immersing solution. From the reduction in sample pH we could also identify the dehydration process created in the sample. The immersion treatment has originated fiber bundle contraction and a spread distribution of the muscle fiber bundles inside. New studies with the mixture used, or with other combinations of its constituents might be interesting to perform with the objective to develop new clinical procedures.

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